I can't see the drawings of the latch, but understand about the latch not cycleling. Can you get the window down?

I would think if so, you might be able to tug and push on the door a bit more than just pulling on the outer door handle.  On trunk issues, of course not mini, I'd drill right through the lock and then activate it with a screwdriver. This might be an option.  Last resort??

I thought about taking the handle off, but one of the screws isn't accessible with the door closed.  

//www.minimania.com/catPage/12-41/12/41/0/Front-Door---Wind-Up-Window-Type

(I couldn't get the Somerford one to show.)

The fact that the plate that the outside button presses is staying depressed is telling. I suspect the latch has not fully cycled. Pushing/pulling on the door while trying to get that plate to move back to its start position may help.

I wouldn't go drilling anything just yet.
It's been a while since I had to mess with a MkIII> door mechanism....but recall it being a nightmare.
I had to replace the door handle completely....it's fidly that's for sure... but wouldn't want to go drilling anything unless no other way

Does the diagram here help...
//www.somerfordmini.co.uk/eshop/index.php?main_page=page&id=38

Thanks Mur.

When I move the inside lock mechanism I can see it moving on the latch.  The plate on the latch that the outside button pushes is still depressed (without the button) and the inside door handle has no effect. It is stuck and won't move.  The long rod just bends if I try to move it.  I have tried holding the rod down and giving the handle some force...no luck.   

I am thinking of drilling the latch bar out from the inside of the car where the bar attaches to the plate.

Once again, tony/robster/specialist gave advice on a subject that he has no actual knowledge of. It is dangerous and he should be banned again, permanently. This is clearly counter to whatever agreement that was made to allow him to return.

The Lock tumbler in the outside door handle attaches to the latch via a clip, whereas the inside lock mechanism lever is attached more permanently. I would begin by articulating this back and forth to see if it is changing anything in the latch and if the inside door handle or outside push button begin to have any effect. I have encountered the outer tumbler clip coming undone, and yet still being held in place by the lever off of the end of the tumbler. Hope this helps.

Ya..no go.

This all started with unlocking the door from the outside, and pressing the button to open.  Something snapped and now I'm stuck.  After taking the door card off, I can see the locking lever that attaches to the outside handle is off and the plate that the button presses on the latch mechanism is stuck like it is being pushed by the button (if that makes sense).

Obviously specialist didn't read before posting, as usual.
Start by pushing hard on the door to close it tighter than normal - the latch bolt may be binding on the strike. Try slipping something in between the door and jamb from the inside to depress the bolt (tongue) of the lock - something like a flexible plastic putty knife. The bolt itself may not be stuck.

Remove the exterior window rubber seal then get a thick wire about 15inches long,  , bend the tip, to make it look like a hook,  then blindly fish for the latch joint extention mechanism ,if you think you got it then pull to open the door, this is a trial and error thing, kinda like carnapping a car. Patience is a virtue!!
 And also make sure that the door is unlocked from the inside.  Goodluck! 

It’s a Mk IV, 78’.  I agree it’s the latch.  Any way to get it open?

What is it? MKI MKII MKIII or later? If it doesnt open from either inside or out it's probably the latch itself.

The latch mechanism on my drivers door has broken with the door shut, it won't open.  I have removed to door card to get to the inside of the door.  It seems like to latch unit is frozen. Yes, its unlocked.

Any ideas on how to get the door open?